This invention relates to a method of inkjet printing in high-efficiency production of hygienic article having print images.
Hygienic articles, such as disposable absorbent articles, including feminine hygiene articles, baby diapers, baby pull-on articles, adult incontinence articles, and the like, including images printed on inner and/or outer surfaces thereof have been disclosed in a copending, commonly assigned U.S. application Ser. No. 10/025,059, filed on Dec. 19, 2001, which is hereby incorporated herein by reference.
The print images can be single-tone, multi-tone, single-color, or multi-color. These images should be visible to the consumer in order to provide the consumer with a variety of desired benefits including improved aesthetics, product functional benefits, or consumer awareness of how good the product is. For example, a two-tone image, shown in FIGS. 1-3, emits a perception of depth, which can be important for the consumer expecting satisfactory liquid absorption and retention capabilities from the product. The perception of depth indicates that although the product is thin, the performance of the product will not be compromised by the thinness.
The print images are generally provided by printing ink on substrate materials by various printing methods, such as flexographic printing, rotogravure printing, screen-printing, inkjet printing, and the like. Typically, the printing operations are accomplished on high-speed printing lines, separately from the converting lines that are dedicated to manufacturing disposable absorbent articles. After printing on the printing lines, the printed substrates are delivered to the converting lines, typically in a form of continuous webs comprising printed images thereon. However, the above practice of separately printing the substrates off the converting lines typically requires additional cost associated with handling, winding and unwinding, storing and shipping of the substrates. In addition, the above steps can negatively affect the quality of the printed substrate, resulting in uneven and often excessive deformations of the wound layers of the substrate inside the roll due to uneven distribution of the compression forces inside the roll. Furthermore, the separately printed substrates often require special registration control methods to ensure proper phasing of the printed images with the converting operations to effect a desired and consistent positioning of the printed image in the produced article.
However, combining the printing operations with converting operations on the converting lines producing disposable absorbent articles at a high-speeds and a high production efficiency can result in substantial production losses, as overall efficiency of the converting line is often compromised. This is due generally to the multiplicity and complexity of the converting operations, wherein any malfunction of any of the converting operations can affect the performance of the printing operation, and vice versa, any malfunction of the printing operation can affect the converting operations. In addition, the printing operations often require periodic maintenance procedures that can also affect the production efficiency of the converting lines. Because converting lines can be high-speed operations, producing hundreds or thousands of hygienic articles per minute, any interruption of the production process can result in substantial production losses.
Therefore, it would be beneficial to provide a reliable method of combining printing operations with converting operations on a converting line for high-efficiency production of hygienic articles having print images.
The present invention can provide a method of inkjet printing in a high efficiency production of hygienic articles, having print images, on a converting line including at least two inkjet print heads. The method includes the steps:
(a) providing a substrate moving in the web direction at a first velocity;
(b) printing on the substrate a first plurality of images by a first inkjet print head disposed in proximity to the substrate, the images are separated from each other in the web direction at a pitch interval;
(c) switching from the first inkjet print head to a second inkjet print head while the substrate continues its movement; and
(d) printing on the substrate a second plurality of images by a second inkjet print head disposed in proximity to the substrate, the images are separated from each other at the pitch interval, wherein the first plurality of images is separated from the second plurality of images by an unprinted region in the web direction, wherein the unprinted region is no greater than 50 times the pitch interval.
In another aspect of the invention, the unprinted region is no greater than 10 times of the pitch interval. In yet another aspect of the invention, the unprinted region is no greater that 1 time of the pitch interval.
In one aspect of the invention, the step of switching from the first inkjet print head to a second inkjet print head can include the following steps:
(a) initiating a second start signal by an operator to a converter controller for starting the second inkjet print head;
(b) ceasing sending a first output signal from the converter controller to the inkjet controller; and
(c) sending a second output signal from the converter controller to the inkjet controller.
In another aspect of the invention, the step of switching from the first inkjet print head to a second inkjet print head can include the following steps:
(a) ceasing sending a first OK signal from the inkjet controller responding to a fail mode of the first inkjet print head;
(b) ceasing sending a first output signal from the converter controller to the inkjet controller, and
(c) starting sending a second output signal from the converter controller to the inkjet controller.
In one aspect of the invention, the high efficiency production of hygienic articles, having print images, on a converting line including at least two inkjet print heads is at least 60% efficiency. In another aspect of the invention, the high efficiency production of hygienic articles, having printed images, on a converting line including at least two inkjet print heads is at least 70% efficiency. In yet another aspect of the invention, the high efficiency production of hygienic articles, having print images, on a converting line including at least two inkjet print heads is at least 85% efficiency.